Las Vegas: Democratic presidential candidate Sen. Hillary Clinton gives her victory speech after wining the Democratic caucuses in Nevada on Saturday. Two thirds of Latinos and 51 percent of the women voters went for Clinton, giving her the edge over Sen. Barack Obama.

Caesars Palace: Supporters of Democratic presidential candidate Sen. Barack Obama wear red Culinary Union shirts and cheer for Sen. Obama. during Saturday's Democratic caucuses in Las Vegas, Nevada. While Sen. Hillary Clinton captured two-thirds of the Latino vote and 51 percent of the women who voted in her victory, Obama received more than 80 percent of the African-American vote.

Las Vegas — It was union brother against union brother, bellhop against bellhop, at the Democratic caucus held inside Caesar's Palace casino. What divided them wasn't hard to see. On Sen. Barack Obama's side sat most of the African-Americans. On Sen. Hillary Clinton's, the majority of whites and Hispanics.

The pattern repeated itself throughout Nevada on Saturday. Two-thirds of Latinos went for Senator Clinton, according to exit polls, and more than 80 percent of blacks chose Senator Obama. The two groups were evenly divided, making up 15 percent of voters. That left white women to decide the vote, breaking 55 percent to 31 percent for Clinton. She won the contest 51 percent to Obama's 45 percent. Former North Carolina Sen. John Edwards won just 4 percent of the vote.

Identity politics have risen partly in response to the racial sparring between Clinton and Obama earlier last week. But more fundamentally, say experts, its prominence highlights the lack of ideological and policy daylight between the Democratic front-runners.

Indeed, the policy portions of the stump speeches this week were numbingly similar. Clinton talked about clean energy providing new jobs that couldn't be outsourced. So did Obama. Universal healthcare was universally promised. Immigration? Both wanted a secure border but no mass deportations.

There were only a few detectable differences. Obama wouldn't mandate everybody to buy health insurance, Clinton would. Obama would increase the Social Security taxes paid by the wealthy; Clinton would not. Clinton wants a 90-day moratorium on home foreclosures. Obama hasn't gotten down to specifics.

Although the race generated great excitement, partly because of the opportunity to elect the first woman or black president, the way voters split represented a setback of sorts for the ideal of a gender-neutral, race-blind society.

"Despite Obama's rhetoric about this being one nation, those things still matter," says Ted Jelen, a political science professor at the University of Nevada Las Vegas. "When I attended my own precinct, you didn't need a sign to tell you which side was supporting which candidate."

To be sure, gender, race, and ethnicity weren't the only factors. Age remained relevant, with Obama capturing the young and Clinton the elderly. The much discussed distinction "experience versus change" split voters, too.

If the trend toward identity politics continues, the Democratic candidates may find themselves battling for African-Americans and Hispanics until a clear winner emerges. Hispanics are numerically stronger out West, African-Americans are more numerous across the South and represent more voters in northern cities.

That doesn't mean, however, that Obama would want to cede California and focus on New York. Democrats typically assign delegates in proportion to the vote breakdown, meaning winning states is secondary now to maximizing delegates, says Dr. Cain. (Republicans, he notes, generally play by a winner-take-all system, meaning that GOP candidates are more likely to target states they'll compete in.)

It's difficult to know which demographic could deliver more delegates. On the one hand, African-Americans in 2004 cast 5 million more votes than Latinos, despite the fact that the Latino population was already the largest US minority. And black voters are more uniformly Democratic.

"These two things would seem to bode well for Obama. The flip side is that Latino voters are more uniformly for Clinton, whereas black women are cross-pressured," says Dr. Schaller.

Yet the Michigan and Nevada results suggest that the racial tensions on the trail have driven African-Americans now solidly into the Obama camp, breaking Clinton's tug on black women.

One of the big wild cards is Mr. Edwards, who garnered 4 percent of the vote here. A significant chunk of voters may be up for grabs if Edwards were to drop out.

Nevada's results contradict the presumption that Edwards's voters would go to Obama, says David Damore, a political science professor at the University of Nevada Las Vegas. "It's not a given that it's an anti-Hillary crowd."

In a final quirk of the record-turnout Democratic caucus here, Clinton won the popular vote, but Obama garnered more voter delegates, 13 to 12, since they are awarded by congressional district. Clinton, of course, got the headline. But momentum doesn't matter so much in her case, argues Dr. Jelen, since she already has plenty of money and exposure.

"Looking ahead, Obama has to win in South Carolina, period," says Jelen. "The electorate [there] is very African-American and not very Hispanic. If he can't win there, it's unlikely he can win anywhere else."